Volcano details

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Volcano details

• Notesgreen

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Types of Lava

• As we talked about last class, there are
  different types of explosions due to the amounts
  of water and silica.
• Similarly, depending on the amount of water and
  silica, the way the lava flows out of a non
  explosive volcano can change.

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4 types of lava

• Lava is based on how it moves out and away from
  the volcano.
• Blocky lava Cool and stiff, it does not travel
  far from the volcano. It usually oozes out after
  an explosive eruption.
• Pahoehoe (pah HOY HOY) slow flowing like wax
  dripping from a candle. It has a rope-like
  appearance.

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4 types of lava

• Aa (AH ah) This lava has a jagged surface and
  pours out of a volcano much quicker. It is
  brittle and hardens quickly, allowing for molten
  rock to flow underneath. It is named after the
  sound you would make if you walked across it
  barefoot.
• Pillow lava The result of lava erupting
  underwater. The water causes rapid cooling and
  results in bubble like pillows.

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Can you identify these lavas?
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Explosive lava

• If it doesnt flow out of the volcano, it gets
  blasted from the volcano. These blasted pieces
  can range in size. Pyroclastic material (or
  pieces shot from the volcano) are classified by
  their sizes.

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Types of pyroclastics

• There are 4 main types/sizes ejected from
  explosive eruptions
• Volcanic blocks Solid chunks of rock blasted
  from the volcano, they are basically chunks of
  the volcano top.
• Volcanic bombs Large blobs of magma that harden
  in the air. They often form tear-drop shapes as
  they fly through the air. They are larger than
  64mm in diameter.

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Types of pyroclastics

• Lapilli (La pill ee) Meaning little stones in
  Italian, these are pebble-like pieces that range
  from 2mm to 64mm.
• Volcanic Ash Particles that are less than 2mm in
  diameter. Ash forms when gases force magma to
  explode into tiny pieces.

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Can you identify these pyroclastics?
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Types of Volcanoes

• Shield Volcano
• Layers of lava from repeated non-explosive
  eruptions.
• Wide with a gentle slope.
• Often the tallest because it is always increasing
  in size, never decreasing.

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Types of Volcanoes

• Cinder cone volcano
• Small volcanic cones made from its own
  pyroclastic material.
• Has a steeper slope with a narrower base.
• They often erode quickly because they are not
  cemented down by lava.

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Types of Volcanoes

• Composite Volcano (Stratovolcano)
• The most common type of volcano.
• They form by explosive eruptions followed by lava
  flows.
• Alternating layers of lava and pyroclastics form
  broad bases with steep sides.

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Craters and Calderas

• Craters A funnel-shaped pit at the top of the
  central vent of a volcano.
• Caldera A large hole formed when the magma
  chamber empties and collapses.

Click here to learn about calderas that form in
the US.
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Build your own volcano

• Volcano Simulator

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Volcano Lab

• Creating the rubric
• Scale of 1-4
• Define categories
• Examples from last year